Because of the shortage of usable land in industrial areas, especially along waterfront sites, there has been a recent trend towards building large industrial complexes, such as power plants, steel mills, and, of course, shipyards on landfill sites. Additionally, there are several projects presently being planned for construction of large intercontinental airports on landfill sites along the coasts of the United States and the Great Lakes.
In conventional landfill construction projects, the fill is generally provided by depositing relatively solid dry materials along the ocean or water bed, or in the case of swamp land, depositing clean dryfill along the swamp until a firm foundation had been established. Due to the enormous expense of trucking in fill, and the time and material necessary, the costs involved for conventional landfilling have become almost prohibitive when compared to the actual costs of the buildings and facilities constructed on the filled areas.
Recently, new techniques of landfilling have been developed involving the hydraulic sandfilling of swampy or underwater sites. Generally, this method uses a slurry of earth and water from a nearby ocean or lake bed which is hydraulically pumped through a large pipe to the fill site. The slurry is deposited on the fill site and the water drains away, depositing the solid material. With this method it is possible to simultaneously dredge the adjacent river or ocean bed while using the fill area as a depository for the dredged material.
When hydraulic landfill is used, the material, which is generally granular in nature, must first be compacted prior to commencing any construction thereon. This fill can be compacted by allowing the sand to naturally settle over a sufficiently long period of time, usually a matter of months or years, depending on the degree of compaction needed, which in turn is dependent upon the type of material and the weight of any contemplated construction. Alternatively, mechanical means can be used to force the water out of the sand thereby achieving compaction. Generally, this involves large rolling drums, which are rolled back and forth over the material, compacting it as it is deposited.
When hydraulic landfill is used, continual mechanical compaction is sometimes impossible because of the high fluid consistency of the fill immediately after it is deposited. Even when sufficient drainage has occurred, rolling is time consuming and generally ineffective for sufficient compaction at substantial depths. Natural settlement is unsatisfactory because of the amount of time necessary during which no construction can take place.
Because hydraulic landfill projects will often require use of up to 20 or 30 feet of fill to form a sufficient base for a foundation, it is necessary that the compaction be uniformly achieved to substantial depths. This becomes especially important in situations where large facilities are to be subsequently constructed. Pounding or rolling the surface to effect compaction will not really provide a sufficient degree of compaction more than a few feet below the surface and it becomes necessary to have some sort of soil penetrating device to compact the soil lower down.
Prior soil compaction systems applicable to hydraulically filled areas and which provide sufficiently deep penetration have employed one of the varying types of penetrating torpedo-type devices which are solid in nature and are lowered down through the soil to some depth. Once lowered, the particular device is set into vibration by a rotating eccentric or other appropriate means, thereby compacting the soil. These prior devices have proven unsatisfactory for certain applications in that they require a separate means for forcing them to a lowered position in the ground, and the hole through which the device is lowered and raised must be back-filled with uncompacted fill, once the device is withdrawn.
It is therefore an object of this invention to provide a method of compacting soil or other granular materials which will provide a relatively high degree of compaction.
Another object of the invention is to provide a method of compacting soil or other granular material which will provide a high degree of compaction to relatively large depths.
Another object of the invention is to provide a method of compacting soil or other granular material which will not require additional material to backfill holes through which the compacting device is lowered into the soil.
Another object of the invention is to provide a method of compacting soil or other granular material which can be operated with a minimum expenditure of time and manpower.
Another object of the invention is to provide an apparatus for the compaction of soil or other granular materials.